But let's not forget about the slow-motion train wreck that started before any of those and still hasn't hit us: state and city pensions.

Joshua Rauh, of the Kellogg School of Management at Northwestern University, and Robert Novy-Marx, of the University of Rochester, estimate that the states’ pension shortfall may be as much as $3.4 trillion and that municipalities have a hole of $574 billion. Mr Rauh calculates that seven states will have exhausted their pension assets by 2020—even if they make a return of 8%, a common assumption that looks wildly optimistic. Half will run out of money by 2027. If pension promises are to be kept, this will place immense strain on taxes. Several have promised annual payments that will absorb more than 30% of their tax revenues after their pension funds are exhausted (see chart 1).

The severity of states’ pension woes was disguised for years, because asset markets were so strong and because of the way states accounted for the cost of pension provision. But the 21st century has been dismal for stockmarkets, where most pension money has been put. State budgets came under huge pressure as a result of the 2008-09 recession, which caused tax revenues to plunge. Meredith Whitney, an analyst who made her name forecasting the banking crisis, believes the states could be the next source of systemic financial risk.

Now the problem is making headlines, especially in California, where taxpayer groups have been highlighting the generous pensions of some former employees. More than 9,000 beneficiaries of CalPERS, the largest state retirement plan, receive more than $100,000 a year.